Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 34,063	$ 32,226	$ 99,973	$ 59,530
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments (Note 7)	(4,755)	10,021	(19,235)	34,888
Pension and post-retirement plan actuarial gains, net of tax (Note 7)	2,651	2,180	8,039	6,321
Total amount reclassified from Accumulated other comprehensive loss, net of tax	0	0	(774)	0
Total other comprehensive (loss) income, net of tax	(2,104)	12,201	(11,970)	41,209
Comprehensive income	31,959	44,427	88,003	100,739
Comprehensive income attributable to noncontrolling interests	(152)	(4,289)	(409)	(3,185)
Comprehensive income attributable to MSA Safety Incorporated	$ 31,807	$ 40,138	$ 87,594	$ 97,554